Scenic Trips
to the Geologic Past Series:
No. 1--SANTA FE, NEW MEXICO, 1968 (50 cents).
No. 2—TAOS-RED RIVER-EAGLE NEST, NEW MEXICO, CIRCLE
DRIVE, 1968 (50 cents).
No. 3--ROSWELL-CAPITAN-RUIDOSO AND BOTTOMLESS LAKES
STATE PARK, NEW MEXICO, 1967 (50 cents.)
No. 4--SOUTHERN ZUNI MOUNTAINS, NEW MEXICO, 1968 (50
cents).
No. 5—SILVER CITY-SANTA RITA-HURLEY, NEW MEXICO, 1967
(50 cents).
No. 6—TRAIL GUIDE TO THE UPPER PECOS, NEW MEXICO, 1967
($1.00).
No. 7--HIGH PLAINS NORTHEASTERN NEW MEXICO, RATONCAPULIN MOUNTAIN-CLAYTON, 1967 (50 cents).
No. 8—MOSAIC OF NEW MEXICO'S SCENERY, ROCKS, AND
HISTORY, 1967 ($1.00).
No. 9—ALBUQUERQUE - ITS MOUNTAINS, VALLEY, WATER,
AND VOLCANOES, IN PRESS.
COVER: Aspen Basin in the autumn
two billion years of earth history
. . . as seen in half a day
CAMEL ROCK
SCENIC TRIPS TO THE GEOLOGIC PAST
NO. 1
SANTA FE
BY
BREWSTER BALDWIN
AND
FRANK E. KOTTLOWSKI
1968
STATE BUREAU OF MINES AND MINERAL RESOURCES
NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY
CAMPUS STATION
SOCORRO, NEW MEXICO
NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY
STIRLING A. COLGATE, PRESIDENT
STATE BUREAU OF MINES AND MINERAL RESOURCES
FRANK E. KOTTLOWSKI, ACTING DIRECTOR
THE REGENTS
MEMBERS EX OFFICIO
The Honorable David F. Cargo .........................Governor of New Mexico
Leonard DeLayo ............................. Superintendent of Public Instruction
APPOINTED MEMBERS
William G. Abbott ..................................................... Hobbs, New Mexico
Eugene L. Coulson, M.D..........................................Socorro, New Mexico
Thomas M. Cramer ...............................................Carlsbad, New Mexico
Steve S. Torres, Jr ....................................................Socorro, New Mexico
Richard M. Zimmerly .............................................Socorro, New Mexico
First Edition, 1955
Second Edition, 1968
drawings by David Moneypenny
photographs by Wayne B. Bera
For sale by the New Mexico Bureau of Mines and Mineral Resources
Campus Station, Socorro, N. Mex. 87801—Price $0.50
Preface
Santa Fe depends primarily on three reservoirs for its water supply. These
reservoirs, which hold almost enough water to satisfy the city's yearly uses, are
filled by the springtime melting of the winter's snows. Growth of the state's
capital city and several years of drought led to the need to use under-ground
water. Wells were drilled for supplementary water on the basis of the technical
study of the geology and water resources of the Santa Fe area, later published as
U.S. Geological Survey Water-Supply Paper 1525.
This pamphlet, which originated the Scenic Trips to the Geologic Past series,
stemmed from this technical study of the geology and ground-water resources
of the Santa Fe area. It attempted to share the fun of geology with the layman,
whether resident or tourist. As the list inside the front cover shows, succeeding
efforts established the series. The response of travelers of New Mexico's
highways and byways to these little guide books has demonstrated the public's
interest in and enjoyment of roadside geology.
The current booklet brings the first-edition material up-to-date and
incorporates changes in format designed to make it more convenient to use.
The authors acknowledge the contributions of Zane Spiegel, then of the U.S.
Geological Survey, in preparing the original booklet, Miss Teri Ray for her
extensive help with this edition, David Moneypenny for the drawings and
sketches, and Wayne B. Bera for the photographs.
1
REGIONAL SETTING
2
Introduction
Each highway out of Santa Fe leads to a different landscape. The
towering and forested slopes of the Sangre de Cristo Mountains, just east
of the city, contrast markedly with the deep gorge of White Rock Canyon,
some miles to the west. The juniper-dotted plain which stretches to the
south and west from Santa Fe gives way on the north to colorful
“badlands.”
The slow but relentless action of geologic processes, working patiently
through the millions of years of geologic time, formed a wide variety of
prehistoric scenes in this area. Oceans slowly flooded in and then drained
off, leaving featureless coastal plains. Ancient mountain ranges gradually
reared their heights, only to be worn down again by ceaseless erosion.
And fairly recently in geologic time, perhaps in the last million years, a
majestic volcanic mountain subsided in a few fiery months to leave only
the remnants we call the Jemez Mountains.
We can glimpse some of the scenes of the geologic past by looking at the
rocks along the roads near Santa Fe. Although the geologist seldom thinks
in terms of number of years, he has accepted estimates of the ages of
geologic events, and these will be included as an aid to imagining the
geologic history. The laboratory of the geologist is all of the outdoors, and
it is well suited for a Sunday outing, for a science-class field trip, or for the
sheer fun of hiking over the hills and down the valleys.
Four brief trips will reveal chapters in the story of the changing
landscapes around Santa Fe. The map in the center of the pamphlet shows
the route of each of the four trips and also shows what geologic formation
is at the surface in each part of the area. The geologic timetable gives some
perspective of the dim past, and the other maps, cross sections, and
pictures help to show the shape and nature of the rock units.
THE CITY
The longest continuously occupied capital and oldest seat of government
in the United States, Santa Fe has a full and colorful history.
Long before the Spanish arrived, Indians had built pueblos (villages) at
several locations in the general area. The junction of mountains, plains, and
the Santa Fe River offered protection, food and wood supplies, farm land,
and water.
In 1598, only 33 years after the founding of St. Augustine, Florida (the
nation's oldest city) and 22 years before the Pilgrims touched Plymouth
Rock, Don Juan de Oñate established the first colony, San Juan de los
Caballeros. The present-day Pueblo of San Juan still proudly bears the
name Oñate gave it. In 1610, he moved his headquarters 28 miles southeast
where later that same year, Don Pedro de Peralta founded the "Villa de
Santa Fe” (Town of the Holy Faith) on the site of an abandoned Indian
pueblo.
3
The Spanish maintained a precarious hold on this most northern outpost of
their frontier (indeed, on their entire frontier, from western Texas to California). Distance from headquarters and necessary supplies—Mexico City—
Durango—Chihuahua, constant political intrigue and strife between representatives of Church and State, and ceaseless raids by Indians made life in the
northern province one of isolation, poverty, hardship, warfare, and fear. For 12
years, from 1680 to 1692, the Indians did "rule" New Mexico again, the tribes
having united in revolt to drive the Spanish south to El Paso del Norte (Juarez).
Don Diego de Vargas reconquered the province and the capital in 1692, ending
the Pueblo Revolt and successfully ensuring Spanish domination.
With the collapse of the Spanish colonial empire by 1825, the new nation of
Mexico assumed sovereignty over New Mexico, as well as the entire
Southwest. Unending internal conflict caused Mexico to neglect and almost
forget her remote, poverty-stricken, harassed citizens in New Mexico. The
opening of the Santa Fe Trail in 1821 brought the first significant contacts with
United States' citizens.
Most Americans associate "Santa Fe" with the Santa Fe Trail, which for
some 59 of the city's 358 years played a significant role in the life of the city
and its appeal to merchants and emigrants from the east. Today, U.S. 85
closely follows the route of the Santa Fe Trail from a few miles above Wagon
Mound to its terminus in the Santa Fe Plaza. In some places across New
Mexico, one can still see the many ruts that mark the Trail.
In 1846, during the war between Mexico and the United States, General
Stephen W. Kearny marched his army to the Plaza in August and claimed the
territory for the United States. New Mexico and the Southwest came under the
jurisdiction of the United States, where they have since remained, except for a
short time in 1862 when General Henry Sibley's Confederate troops briefly
occupied Santa Fe during the Civil War.
Thus, Santa Fe has known Indian, Spanish, Mexican, American, and
Confederate rule.
The advent of the railroad in 1880 doomed the Santa Fe Trail as a commercial route and started the decline of the city as a rip-snorting trading center.
The steep grades proved too severe for the railroads of that day to negotiate and
the line had to bypass the capital on its way to Albuquerque. Its main line
passes through the station at Lamy, about 17 miles south of the city, where
passengers may take the bus into Santa Fe.
As you drive about the city and visit its many attractions, see how Santa Fe
easily, gracefully, and unmistakably reflects the three major cultures that have
affected it Indian, Spanish, and American.
The original Spanish PLAZA still serves as the hub of the city and center for
municipal activities, from art shows to concerts to dances to religious
ceremonies to parades to pageants. You cannot miss the PALACE OF THE
GOVERNORS, the long, low building distinguished by the row of wooden
pillars that takes up the entire north side of the Plaza. Indians from nearby
pueblos offer jewelry, pottery, and other items for sale, under the protection
4
PALACE OF THE GOVERNORS
of its wide portal. Built in 1610 and occupied continuously by governors of
New Mexico until 1909, the Palace has since housed collections of the Museum
of New Mexico and, more recently, exhibits of the New Mexico Historical
Society and the School of American Research. On the northwest corner of the
Plaza, across from the Palace of the Governors, stands the NEW MEXICO
MUSEUM OF (FINE) ART, which emphasizes fine arts of the Southwest.
Just off the southeast corner of the Plaza, La Fonda—the Harvey House at
the ‘end of the line’—occupies nearly the entire block. Beyond it towers the
CATHEDRAL of St. Francis at the head of San Francisco Street. Archbishop
John B. Lamy, first non-Spanish priest in the newly created American diocese,
built the cathedral in 1869 on the site of a church erected in 1622. He served as
the model for "Bishop Latour" in Willa Cather's well-known novel, Death
Comes for the Archbishop, and now lies buried, with others, beneath the high
altar. Many of the French family names one now comes across in this area
belong to descendants of workmen Archbishop Lamy recruited from France to
build the cathedral.
Low mounds of earth about 1000 yards northeast of the Plaza mark the site
of Fort Marcy, constructed in 1846 by General Kearny.
SAN MIGUEL MISSION church, south from the Plaza on College Street,
dignifies the corner of what looks like a very narrow alley—De Vargas Street.
Historians consider the church "early seventeenth century" and the first one in
Santa Fe. It contains early paintings on hides and the original
5
SAN MIGUEL MISSION
church bell. East of the church, De Vargas Street merges into CANYON
ROAD, an old Indian "highway" and for more than a quarter of a century the
heart of Santa Fe's famous art colony.
Nine INDIAN PUEBLOS lie within easy driving range of the capital and
include San Juan, where the Spanish established the first colony in New
Mexico; San Ildefonso, home of Maria Martinez, internationally famous potter;
and Taos, the state's only occupied multistoried pueblo.
6
Trip 1
TESUQUE FORMATION - SANTA FE GROUP
Landmarks—Camel Rock--Bishop's Lodge
To Circle Drive, 3 miles north of the Plaza to locate the principal landmarks.
Then north to Camel Rock and return through Tesuque and past Bishop's
Lodge. Round trip distance, 25.5 miles; driving time 45 minutes.
0.0 Leave Plaza from northeast
corner. Drive four blocks
north on Washington Street.
0.3
0.3 TURN LEFT at the oval
around the Federal Building
on the north side for one
block to west.
0.1
0.4 TURN RIGHT onto old U.S.
285-84-64, drive north up
hill. As you ascend hill, the
left road-cuts are in pink-tan
silt, sand, and gravel of the
TESUQUE FORMATION
of the SANTA FE GROUP
—geologic
terms
that
indicate divisions of rock
units within broad age
groups. Ancient streams
deposited these
sediments in late Tertiary
time (see geologic timetable,
p. 16).
1.8
2.2 Junction with new U.S. 285-84-64 bypass on left; BEAR RIGHT.
0.3
2.5 Roadcut on left; local erosional unconformity in the Tesuque Formation,
formed when streams eroded briefly during deposition of the formation.
7
LOCAL EROSIONAL UNCONFORMITY IN TESUQUE FORMATION
0.2
2.7 BEAR RIGHT onto black-topped road (for short distance) of Circle Drive.
0.9
3.6 STOP A at metal gate on right. The panoramic sketch will identify the
mountains visible from this point. Notice lovely expensive homes nearby.
To the east are the Sangre de Cristo Mountains. To the southwest in the
far distance are the Sandia Mountains just east of Albuquerque. The
higher parts of this range consist of the same ancient rocks that make up
the Sangre de Cristos. Halfway to the Sandias are the Cerrillos ("little
hills"), to the left of which are the Ortiz Mountains. The Ortiz Mountains
and the Cerrillos are part of a north-trending chain of moderately young
igneous rocks (rocks formed from the cooling of molten rock). In this
igneous chain of hills are deposits of zinc, lead, silver, copper, gold, and
turquoise. The turquoise was mined by the Pueblo Indians centuries
before the Spaniards arrived. It was
PANORAMA FROM CIRCLE DRIVE
8
a famous product of Spanish New Mexico and is a trademark of the
"Land of Enchantment" today.
Turning toward the north you see the "badlands" of the Española
Valley, where soft pinkish-tan sandstone is almost the only rock visible.
This soft rock is readily weathered into bizarre shapes, such as "Camel
Rock," 13.7 miles north of the Plaza on the west side of the highway.
You may find fossil bones in these pinkish beds, because famous collections of late Tertiary fossil mammals have been assembled from these
beds around Española.
To the northwest, forming the high, even skyline, are the Jemez
Mountains. Los Alamos is on the plateau sloping toward you, and
Bandelier Monument is in one of the many deep canyons that gash the
plateau. The canyons drain into the deep gorge of White Rock Canyon of
the Rio Grande, but the canyon can't be seen until one gets on the very
rim. As a matter of fact, there are only a few roads giving a glimpse of
the canyon, that to Buckman and N. Mex. 4 to Bandelier National
Monument being the easiest to drive.
The sand and gravel hills a couple of miles to the west hide most of the
lava mesa (Mesa Negra) between White Rock Canyon and the Santa Fe
area. However, Tetilla Peak, the most prominent pointed hill on the lava
mesa, is visible. On a clear day, the volcanic pile of Mt. Taylor appears in
the saddle between Tetilla Peak on the left and the Jemez Mountains on
the right; Mt. Taylor is 100 miles west-southwest of here.
We have been looking at parts of the Rio Grande trough, which forms
an irregular belt 20 to 50 miles wide and trends southward from Colorado
toward the south part of New Mexico. The Rio Grande Valley lies in this
structural trough. The old rocks are deep below the surface in its center,
but they form the Sangre de Cristo Mountains, the Sandia Mountains, and
other ranges on its borders. The rocks in the trough include not only
thousands of feet of sand and gravel brought in by rapidly flowing
streams, but also large amounts of moderately young volcanic material.
But to have the old rocks forming mountains and the young rocks
underlying the lower elevations—that is upside down! In the Great
Plains, and on the Colorado Plateau along the Grand Canyon, we see
older rocks below and younger above. This is the normal sequence. But
along the Rio Grande trough the younger beds were in the wide
SHAPE OF THE RIO GRANDE TROUGH
9
4.2
4.4
4.6
4.8
5.5
10
belt that dropped down while its borders rose into mountain ranges. The
amount of vertical movement may have been as much as five miles in
places. Near Los Lunas an oil test drilled through 9000 feet of basinfilling sand and gravel, although another 5000 feet of the same material
had apparently already eroded away.
The up-and-down movement was not simple, for it has left a jumble of
fault blocks, each one displaced vertically a few hundred or thou-sand
feet from the next. This mountain-building caused many earthquakes, but
it must have taken several million years if the rate was similar to the
mountain-building in California today.
0.6
STOP B at turnout on the left in front of house, at the south end of the
ridge overlooking Santa Fe and the Bishop's Lodge highway. From here
we can see more of the details of the Santa Fe area proper. The center
map shows the distribution of the main rock units, and the geologic
timetable lists the sequence of units and geologic ages.
Along the east edge of the area are the foothills of the Sangre de Cristo
Mountains, which are here composed of Precambrian and Pennsylvanian
rocks. In the southwest corner of the area are many small hills which lie
just north of the Cerrillos and which, like the Cerrillos, are made of midTertiary volcanic rocks. The juniper-dotted plain that slopes westward
from the mountains across most of the area is underlain by the youngest
beds of the "Santa Fe Group."
This Group consists of soft sandstone, sand, silt, and gravel of late
Tertiary and perhaps Quaternary age. The pinkish-tan soft sandstone and
gravel we see along Trip 1 belong to the Tesuque Formation of the Santa
Fe. Along the north edge of the area, this plain is being cut up into the
"badland" topography that is typical of the Tesuque Formation outcrops
farther north around Española. To the west is the lava-capped mesa,
Mesa Negra, which projects eastward to the west edge of our area.
0.2
Junction with N. Mex. 22; TURN RIGHT toward Santa Fe.
0.2
Junction with Camino Encantado; TURN RIGHT toward good view
westward of Jemez Mountains on western skyline.
0.2
Roadcuts on both sides of Camino Encantado of Tesuque Formation
gravelly sandstones unconformable on pink clayey silts.
0.7
Junction with U.S. 285-84-64; TURN RIGHT toward Camel Rock
region. As highway descends hill, on right are many roadcuts in
Tesuque Formation.
SCOTTISH RITE CATHEDRAL
1.1
At sign "Tesuque Turn Off 1000 feet" and junction with dirt road from
right, notice flat-topped ridge straight ahead on right side of highway.
This gravel-capped hill is a remnant of an ancient higher level of the
streams in this area.
2.1
8.7 SANTA FE OPERA turnoff, left. Founded in 1957 by its general director,
John Crosby, the Santa Fe Opera Association rebuilt and expanded its
facilities following a disastrous fire in 1967. The new design incorporated
a fifty per cent increase, both in area and volume, over the original
theater, although the sweep and height of its canopy give the same openair feeling. The audience can still view the lights of Los Alamos, thirty
miles distant, through an opening at the back of the stage. Internationally
renowned, the Opera has presented more than forty-five operatic works
(including at least nine American and two world premieres), most of
them in English though a sprinkling retains the German, French, Italian,
and Russian lyrics. An apprentice program provides singers for the
chorus and minor roles. Some operatic
6.6
11
headliners have appeared at this "opera under the stars"; many others
who made their debuts here have since attained worldwide recognition.
Its season usually runs from mid-June or the first week of July through
August.
Straight ahead on skyline, the even surface sloping gently westward is
the remnant of an ancient, high-level stream bottom.
0.9
9.6 Highway crosses Rio Tesuque.
2.4
12.0 JUNCTION, left, road to Tesuque Pueblo. Always a small village,
Tesuque (from Spanish approximation of Indian term for "spotted dry
place" because the Rio Tesuque disappears in the sand and comes to the
surface only in some spots) holds a major place in New Mexico history.
Here occurred the murder that heralded the Pueblo Revolt of 1680 and
prompted the Indian leaders to change the date of the uprising from
August 13 to August 10. Primarily farmers, the Tesuque Indians do not
have good-quality handicrafts, but they present colorful and authentic
ceremonials and have retained, much of their early culture.
1.7
13.7 CAMEL ROCK. Turn left across the highway into the parking area.
Weathering of the soft sandstone of the Tesuque Formation shaped this
camel-like rock and the other bizarre forms that characterize the
Española Valley. Fossil bones may occur in these pinkish beds, for
OUTCROPS OF TESUQUE FORMATION EAST OF CAMEL ROCK
12
BISHOPS LODGE IN FOOTHILLS
famous collections of fossil mammals have come from those around
Española ("new Spain"; "Spanish lady").
Before you leave the parking area, notice the hills of this interesting
formation across the highway from Camel Rock; paying particular
attention to the slightly tilted layering effect in the middle sections and
the typical badland ruggedness caused by erosion in the area to your
right. Also toward the right, notice the white "streak" across a spur of the
rough, eroded rocks, as well as directly across the highway: beds of
pumicite. They were blown out of a distant volcano and interbedded with
the Tesuque Formation's stream deposits.
These hills mark the southern edge of the badland topography around
Pojoaque (possibly "drink water place" or "place where the flowers grow
along the stream") and Española.
TURN AROUND; take U.S. 285-64-84 back toward Santa Fe.
3.7
17.4 Junction; TURN LEFT onto N. Mex. 22 to Tesuque village. Do not
confuse this place with the Indian pueblo. The route parallels the Rio
Tesuque part way. This lovely valley offers many picturesque scenes for
your camera of small farms and casas against the mountain back-drop.
0.8
18.2 On northern edge of Tesuque suburbs, highway is on ancient stream
bottom 15 to 20 feet above present stream bed; this is a "terrace" whose
sands and gravels were laid down 2200 to 1200 years ago; then a lower,
deeper stream valley was cut until about 1880 when the present stream
channel and its flood plain were formed. The lower terrace, 8 to 10
13
feet above the present stream bed, is to the right of the highway, below
the 10-foot bench scarp. It was Rio Tesuque's stream bottom level during
the period from 1200 to 1880.
1.0
19.2 Junction (beyond El Nido nightclub); take LEFT FORK, Bishop's Lodge
Road.
3.0
22.2 Bishop's Lodge turnoff to left. Clear, swift, cold stream running through
the Lodge's grounds is Little Tesuque Creek; it will be seen upstream on
Trip 2.
0.2
22.4 To left, you can see the roadcut made by the old highway across the
middle of the knoll; ahead in right roadcut are same light-gray tuffaceous
sandstones of the Bishop's Lodge Member of the Tesuque Formation.
Cobbles of volcanic rocks are scattered through this gray bed, suggesting
volcanic eruptions during its formation.
0.6
23.0 In right roadcut is weathered dark-green olivine basalt. This volcanic flow
rock also crops out in deep gully left of the highway; again, it tells of the
volcanic activity during the late Tertiary when the lower part of the
Tesuque Formation was being deposited.
0.5
23.5 Junction from right of Circle Drive. Good view straight ahead of Ortiz
and Sandia mountains on southern skyline.
OLD ROADCUT IN LIGHT-GRAY TUFFACEOUS SANDSTONES
14
GOVERNOR'S MANSION
0.9
24.4 Mansion Drive intersection. Side trip to right to top of hill gives view of
GOVERNOR'S MANSION.
0.7
25.1 Federal Building on right; keep straight ahead.
0.4
25.5 Plaza; end of Trip 1.
15
GEOLOGIC TIMETABLE
16
Trip 2
PRECAMBRIAN AND PENNSYLVANIAN ROCKS
Hyde Memorial Park Road
Up the Hyde Park Road to Little Tesuque Creek, 5 miles northeast of the
Plaza to see Precambrian and Pennsylvanian rocks, then up to Hyde Memorial
State Park and the ski basin road. Round trip distance, 17.5 miles; driving time,
45 minutes.
The rocks that make up the Sangre de Cristo Mountains just east of the city,
and indeed in the eastern part of the city, are largely Precambrian in age. North
of the Santa Fe River, Pennsylvanian sediments form sheets that rest on the
Precambrian rocks.
The word "Precambrian" is quite significant, for it refers to the oldest rocks
of the earth. Precambrian rocks represent our record of the first three quarters of
geologic time, and yet they are lumped under one term. They are older than
rocks of the Cambrian, which is the first period of geologic time during which
fossils record an abundance of life. The fossils help to show the relationships
between rocks of different areas and also to interpret the origin of these rocks.
And so the absence of fossils in Precambrian rocks makes it difficult to
understand them.
The Precambrian rocks near Santa Fe
include pink, green, and gray rocks, with
many mineral crystals and usually with a
banded or a streaked appearance. These rocks
can be seen in several places near Santa Fe.
They are well exposed in roadcuts along U.S.
85 between 5 and 10 miles southeast of the
city on the Las Vegas highway. We shall see
Precambrian rocks on Trip 2, which takes us
northeast of Santa Fe on the Hyde Park Road.
0.0 Leave northeast corner of Plaza, jogging
northward onto Washington Street.
0.3
0.3 Federal Building on left; keep straight,
past Scottish Rite Cathedral.
17
GRAVELS OVER LIGHT-GRAY SANDS NEAR JUNCTION OF N. MEX. 475 AND
GONZALES ROAD
0.2
0.5 TURN RIGHT onto Artist Road (N. Mex. 475) at signs for ski area and
Hyde Park.
1.5
2.0 Junction with Gonzales Road from right; sign on right "Santa Fe Ski
Basin, 15 miles." In left roadcut, the light-gray tuffaceous sands of the
Bishop's Lodge Member of the Tesuque Formation are overlain
conformably by coarse gravels washed from the mountains during more
recent time. For the next two miles, roadcuts are of Precambrian rocks:
pink granite, faintly banded, called granite gneiss (composed of pink
feldspar and glassy quartz) intruding green schist (thinly banded rock).
1.8
3.8 Side road to right to Hyde Park Estates. Twisted and contorted pink
Precambrian granite gneiss in roadcut to left.
0.3
4.1 Rancho Elisa on left. Beds of Pennsylvanian rocks ahead in roadcuts on
right.
0.5
4.6 Fossiliferous Pennsylvanian limestones interbedded with shales in right
roadcut. Roadcuts ahead in thick limestone; then abruptly along a vertical
contact, crumbly Precambrian rocks to the north. The Penn-
18
sylvanian sedimentary rocks are in contact with the weathered Precambrian along a break in the earth's crust, a geologic "fault."
0.7
5.3 STOP C. Turnout on right after crossing culvert over Little Tesuque
Creek. Across the road and on the north bank of the creek about 200 feet
to the west is a huge vertical wall-like mass of rock. It is worth walking
over to see, for it consists of angular pieces of granite glued together by a
very fine-grained granite "powder." This "breccia" (broken rock)
represents massive granite that was shattered and re-cemented along a
fault (slipping of rocks along a break). Many such masses of granite
breccia can be found east and southeast of Santa Fe.
GRANITE BRECCIA AT STOP C
19
6.3
8.3
8.5
11.8
12.2
20
A few feet to the right of the breccia there is a prospect tunnel. The
coarse pink granite on the right intruded the gray banded schist. This is
the same relationship we noted three miles back along the road. The
thinly banded schists may have been originally sand or mud, or they may
represent volcanic rocks; in any case they have been so altered in form
(metamorphosed, changed) by heat and pressure, and by the heat and
chemical attack of granite intrusions, that there is little hint of their
original nature.
Up the road from the parking turnout, in the left roadcut, the coarsegrained pink granite that has intruded the gray banded schist forms both
sills (intrusions that run parallel to the bedding or banding of the "host"
rock) and dikes (tabular masses of intruded rock that cut across bedding).
The massive dark-green rock is amphibolite, being made up mainly of
green laths of the amphibolite mineral, hornblende.
1.0
Pavement ends; as road climbs into the mountains notice the change in
trees from piñon to ponderosa pine, then aspen, and in the highest timber
zone, spruce and fir. The white-barked aspen begins in the valleys at
Black Canyon camp ground. Precambrian rocks in all roadcuts.
2.0
Enter Hyde Memorial State Park. Camping and picnic tables.
0.2
Parking on right for lodge and store of Hyde Park. TURN AROUND. (Or
if you wish to drive it, the road continues nine miles up to the ski basin
and Ski Lodge with numerous beautiful mountain views, especially of the
aspen basin in the autumn. Roadcuts and outcrops are of Precambrian
rocks.)
3.3
Cross culvert over Little Tesuque Creek near Stop C. As road ascends hill,
notice that the Precambrian granite gneiss (a gneiss is a coarsely banded
rock) is badly shattered and deeply weathered to a rotted mass of half
rock and half soil—it is a fossil soil near the top of the hill that formed
before the Pennsylvanian sediments were laid down, some 300 million
years ago.
0.4
STOP D. Pull off on narrow right shoulder of road just beyond right-angle
curve. In roadcut on left, thick-bedded Pennsylvanian limestones abut
against the crumbly, rotten Precambrian granite gneiss; their contact is a
vertical plane, a FAULT. The massive limestones on the right, south side,
of the fault are normally much higher than the Precambrian granite
gneiss; thus they have been dropped to their present position. If you
climb up onto the hilltop above the roadcut,
LA BAJADA HILL AREA
you can find the basal Pennsylvanian sandstone and shale unconformable
on the Precambrian, resting on the fossil soils derived from the granite
gneiss.
0.2
12.4 STOP E. Pull off on narrow right shoulder or at turnoff near culvert on left
side of road. Reddish shale and limestone downhill are in basal part of
Pennsylvanian beds and are not far vertically above the hidden
Precambrian granite gneiss. Eastward along the highway, the Pennsylvanian sedimentary rocks are mostly brown sandstone and shale.
Fossils! The limestone ledges here have many fossils. The series of ¼inch discs with hollow centers are parts of crinoid stems. These stems
were the attachment of a cup-shaped marine animal; such "sea lilies"
inhabit some oceans today. The nut-shaped shells with ridges are
brachiopods of several kinds. These and other kinds
of fossils have weathered out of the rock and can be
found in the loose debris just below the limestone
ledges. Weathering is now etching other fossils into
relief on the limestone ledges. The abundance of
21
FOSSILIFEROUS LIMESTONES AT STOP E
13.0
15.0
16.0
16.1
16.2
16.3
22
shell fragments in the rock suggests that the limestone represents a sand
of shell particles that accumulated in a surf zone near the shore.
0.6
Entrance to Hyde Park Estates on left. Road is back
into Precambrian rocks; roadcuts of pink granite that
intruded and "digested" the green schist.
2.0
Junction with Gonzales Road, paved; BEAR LEFT.
1.0
On left, pinkish Tesuque Formation faulted down
against Pennsylvanian limestone and shale.
0.1
Pennsylvanian sandstone, coal, shale, and lime-stone
in quaries on right.
0.1
Road crosses contact with Precambrian rocks on left
and Pennsylvanian on right.
0.1
TURN RIGHT onto Cerro Gordo Road, which
parallels the north side of the Santa Fe River and westward merges with
Palace Avenue.
1.2
17.5 Northeast corner of PLAZA. End of Trip 2.
On the Hyde Park trip, we saw Pennsylvanian sedimentary rocks resting on
Precambrian metamorphic rocks. The marine fossils indicate that a sea was
there, and some of the sandstone and coal beds were formed by streams and in
swamps on land. The shoreline of a Pennsylvanian sea must have moved back
and forth across this area. Regional studies suggest that not many miles to the
northwest there was a mountain range at the same time, projecting southward
from what is now Colorado.
But where are the rocks of the Cambrian to Mississippian periods? Most of
these are not found until we go to central and southern New Mexico around
Socorro and Truth or Consequences. Indeed, the area in which Pennsylvanian
beds rest chiefly on Precambrian rocks includes much of northern New Mexico
as well as parts of southern Colorado and northwest Arizona. There are some
remnant patches of Mississippian limestone and sandstone between the
Pennsylvanian and the Precambrian—a small block along Little Tesuque Creek
between the Hyde Park Road and Bishop's Lodge, many remnants along the
Pecos valley to the east, and others—but we infer that for the most part there
was a landmass that was being eroded for much of the long period from
Cambrian to Mississippian time. Some sediments, such as the Mississippian
limestone and sandstone, were deposited during this period but were eroded in
most areas before the Pennsylvanian.
PERMIAN THROUGH CRETACEOUS ROCKS
After the Pennsylvanian Period, there is another long gap in the geologic
record near Santa Fe. No rocks near the city represent the Permian, Triassic,
Jurassic, or Cretaceous periods. However, rocks of these ages are exposed along
Galisteo Creek near Cerrillos. Permian and Triassic sedimentary beds can be
seen around Canyoncito, 13 miles southeast of Santa Fe on U.S. 85, and
Triassic, Jurassic, and Cretaceous rocks are well exposed on the north side of
Galisteo Creek, 2 to 5 miles east of U.S. 85, 22 miles southwest of Santa Fe
along La Bajada Hill.
These rocks were deposited in the Santa Fe area but have been buried by
younger beds or removed by erosion. The Permian through Cretaceous sediments represent a fluctuation of marine and nonmarine conditions. The coal at
Madrid to the south is Late Cretaceous in age and formed on the coastal plain of
the last large sea to invade north-central New Mexico.
23
Trip 3
EOCENE - OLIGOCENE - MIOCENE
"Garden of the Gods," Cerrillos, Turquoise Hill, La
Bajada Hill, and Cienega
GALISTEO FORMATION
Late in the Cretaceous Period, the flat coastal plain gave way to rising
mountains. This mountain chain was a forerunner of the present Rocky
Mountains. Later geologic events have obscured the exact limits of the Eocene
mountainous areas around Santa Fe. But there was a basin where Lamy,
Galisteo, and Madrid are now. Streams that headed in these highlands carried
sand, mud, and gravel into the basin to make up what we call the "Galisteo
Formation."
To "Garden of the Gods," Cerrillos, Turquoise Hill, La Bajada Hill, and
Cienega southwest of Santa Fe—to see Eocene to Miocene sediments and
volcanic rocks. Round trip distance, 72 miles; driving time, 2 hours.
0.0 Leave Plaza; go southwest to join Cerrillos
Road (U.S. 85) south
toward Albuquerque.
1.3
1.3 Junction with St. Francis Drive at Traffic light;
continue straight ahead
on Cerrillos Road.
1.8
3.1 Traffic light at junction with
Osage Avenue, U.S. 85
bypass.
1.2
4.3 Notice bluff on the north
side of Santa Fe River, to
the right; a
similar rise in ground is on
the left to the south. We are driving along the floor of an earlier, higher
valley of the Santa Fe River.
26
LOOKING SOUTH TOWARD VERTICAL PALISADES OF GALISTEO FORMATION AND
GALISTEO VALLEY WITH ORTIZ AND SANDIA MOUNTAINS ON SKYLINE
6.2
8.7
9.8
1.9
Junction to municipal airport; KEEP LEFT on U.S. 85.
2.5
Pumice (white frothy particles blown out of a volcano) in roadcuts.
1.1
Junction, TURN LEFT onto N. Mex. 10.
2.4
11.2 New Penitentiary on right (west).
5.0
17.2 Continue straight ahead; junction with N. Mex. 22 from right. It leads
west to Picture Rock.
3.8
21.0 Vertical palisades of sandstone on right.
0.2
21.2 STOP F at turnout near Broken Hill Ranch. The vertical beds of red
mudstone and yellow sandstone, which make a miniature "Garden of the
Gods," are part of the Galisteo Formation. Geologic formations are
named for geographic features; this unit was named for Galisteo Creek,
which lies just to the south between here and the Ortiz Mountains.
Two kinds of fossils have been found in the formation not many miles
from here, petrified wood and mammal bones. The wood, mostly
27
pine, is abundant at Sweet's ranch, a mile southeast of Broken Hill Ranch.
The bones have been identified as late Eocene titanotheres. The
titanothere is extinct, but, according to the people who like to put old
bones together, it resembled a moronic rhinoceros.
From the fossils and other characteristics of the Galisteo Formation, it
is evident that the sand and mud were carried into a basin by streams in a
climate more humid than today's climate. Some of the streams must have
flowed rapidly in flood-time to carry the boulders and pebbles visible in
some of the beds.
If sediments such as these sandstones and mudstones are deposited as
horizontal sheets, why are the beds standing on end? In this area, the beds
were tilted to their present vertical position by a mass of hot, pasty rock
that forced its way upward from a mile or more below the surface.
Several such igneous intrusions make up the Cerrillos, a few miles to the
west.
1.4
22.6 Roadcuts of reddish Galisteo Formation beds.
"GARDEN OF THE GODS"
STEEPLY DIPPING BEDS OF GALISTEO FORMATION AT BROKEN HILL RANCH
28
0.5
23.1 Roadcuts in vertical, contorted black shale and tan sandstone of the
Cretaceous Mesaverde Formation. These marine beds are some of the
youngest Cretaceous rocks in the region.
0.8
23.9 Ridge to right of highway capped by massive monzonite rocks intruding
black Mancos Shale. The marine Mancos Shale is one of the older of the
Cretaceous units in this area.
0.3
24.2 Junction with road to Cerrillos; TURN AROUND. N. Mex. 10 continues
south across Galisteo Creek to Madrid. To the north on the other side of
the A. T. and S. F. Railway tracks, and on the north side of the valley, the
black Mancos Shales are capped by high-level stream gravel and intruded
by the monzonite sills at the east end of the shale cliff.
1.1
25.3 Roadcuts again in vertical Mesaverde Formation beds. To left in distance,
to northeast, horizontal beds of the Santa Fe Group are unconformable on
steeply dipping Cretaceous and Galisteo layers.
1.9
27.2 Garden of the Gods, again.
VERTICAL MESAVERDE FORMATION SHALE AND SANDSTONE
29
PICTURE ROCK
0.3
27.5 In left roadcut, Santa Fe Group pink sands unconformable on yellowish
Galisteo beds.
0.8
28.3 Side road, right, to village of Galisteo.
1.5
29.8 Cross Arroyo Coyote; notice the water from Coyote Spring here and also
the volcanic rocks in the stream bed.
1.4
31.2 Junction with N. Mex. 22; TURN LEFT.
0.8
32.0 "Picture Rock," a butte of igneous rock on left. The Cerrillos, straight
ahead, and the other knobs and hills around here are of similar kinds of
rock.
0.6
32.6 Highway makes right-angle curve to right.
1.0
33.6 Right-angle curve to left.
0.3
33.9 STOP G. The many prospects and mine workings on Turquoise Hill, to
the north, date back at least to the turn of the century, and pos-
30
sibly centuries earlier. Perhaps $2,000,000 worth of turquoise was won
from Turquoise Hill. Another famous turquoise mine, Mt. Chalchihuitl, is
in the middle of the Cerrillos and was worked by the Indians before the
Spanish arrived. Hike the 1000 yards to the north to see the old workings.
VOLCANOES
Deposition of the mud and sand of the Galisteo Formation was ended
when volcanic outpourings blocked and choked the streams. Lava, ash,
and bouldery flows covered much of the surface west of Santa Fe. There
was a north-south belt of volcanic centers that included the Ortiz
Mountains, the Cerrillos, and the Cienega area. The purplish-gray rocks
seen back in Arroyo Coyote are volcanic rocks; the grayish intrusive
rocks of Picture Rock and Turquoise Hill are monzonites related to the
volcanic rocks. These are called the Espinaso volcanics.
1.0
34.9 Right turn; Cerrillos to west; base-metal mines (lead and zinc) have
produced some ore from the Cerrillos in the past.
0.4
35.3 Continue straight ahead; side road from left from Cerrillos; good view to
north.
VIEW NORTHWEST FROM CERRO DE LA CRUZ ACROSS THE CIENEGA AREA
TOWARD THE JEMEZ MOUNTAINS. U.S. 85 IN LOWER PART OF PICTURE
31
ROADCUT AT 43.6. MORRISON ON LEFT FAULTED AGAINST
MANGOS AT EXTREME RIGHT OF PHOTOGRAPH
1.7
37.0 Bridge across Alamo Creek. Water again in this lush, grassy valley.
Bonanza Hill is ahead to right; Cerro de la Cruz is the black cone-shaped
butte ahead to left. The mound just to our right in the valley was the site
of a mill that treated the lead-zinc ore from the Cerrillos in the 1880's.
There is no trace now of the mining camp of Bonanza, which was on the
hill just behind us.
0.2
37.2 Curve to left.
0.9
38.1 Junction with U.S. 85 at Turquoise Trading Post. TURN LEFT onto U.S.
85, drive southwest toward La Bajada Hill and Albuquerque. Sandia
Mountains on southwest skyline; La Tetilla Peak to northwest with Jemez
Mountains on northwest skyline.
0.6
38.7 Bridge over Alamo Creek; note swampy stream bed.
1.1
39.8 Low ledges of black basalt to right beyond fence. These basalt flows were
extruded from the basalt volcano ahead on the right.
1.1
40.9 Crest of hill on curve to right; basalt volcano cone to right.
1.8
42.7 Begin descent of La Bajada Hill. Calichified (rich in lime) gravels and soil
on top of black basalt flows at top of hill. Basalt is vesicular (full of holes
from ancient gas bubbles) and flow banded. In left roadcut below the
basalt are pinkish silts and clays of the Santa Fe Group, partly baked
when the hot basaltic lava flowed over them.
32
CHANNEL-FILLING SANDSTONE IN GALISTEO FORMATION
0.2
42.9 In left roadcut, greenish-gray to gray-black Cretaceous Mancos Shale cut
by vertical dark-gray dike of intrusive rock called "limburgite." Pinkish
Santa Fe Group beds above the Mancos.
0.7
43.6 In left roadcut, the yellow-brown sandstones and gray shales, cut by the
reddish-purple, nearly vertical igneous dike, are beds of the Morrison
Formation. These rocks are older than the Cretaceous Mancos Shale,
being of Jurassic age, about 145 million years old. They were deposited
on vast flood plains and in and near meandering streams. To the north
near Rosario, they overlie the Todilto gypsum, another Jurassic rock unit.
At the west end of the left roadcut, the yellowish Morrison sandstones
are in vertical contact with blackish-gray Mancos Shale—another
geologic fault that broke the rocks, the Mancos Shale on the west being
down-dropped along the fault against the older (therefore lower in the
rock sequence) Morrison beds.
In the broad valley to the north on the right side of the highway, reddish beds of the Galisteo Formation crop out; these are on the west side of
another fault along which they were dropped down to the level of the
Mancos Shale. Most of the La Bajada escarpment is a series of complex
faults, with the down-dropped blocks on the west side—this is how the
land surface has been affected by the geologic structure to show the
change in rock elevation from the basalt-capped Santa Fe plateau down to
the Rio Grande Valley.
0.2
43.8 High roadcut on right is of the greenish-gray Espinaso volcanic rocks,
here mostly conglomerates with the cobbles of volcanic materials. The
33
GALISTEO FORMATION OUTCROPS ON LA BAJADA HILL
lenticular beds dip to the northeast; thus another fault has been passed
since the previous roadcut, with the Espinaso units dropped down to the
west. The Espinaso beds grade downward into the Galisteo layers in the
valley to the west.
0.1
43.9 Roadcuts in reddish sandstone, siltstone, and claystone of Galisteo
Formation. The massive, lenslike sandstone in the upper part of the right
roadcut is a channel sandstone, deposited near the center of an ancient
stream during Eocene–Oligocene time.
Typical outcrops of the Galisteo Formation occur in the right roadcut a
few hundred feet downhill, near the highway sign; lenticular beds of
pebbly sandstone, massive siltstone, and silty, layered shale and
claystone, all various hues of reddish brown.
0.8
44.7 Bottom of La Bajada Hill. Outcrops on both sides of highway are of
pinkish Santa Fe Group beds, partly covered by local stream wash sands
and gravels. Again a large fault has been crossed, between the Galisteo
and the Santa Fe rocks, with the Santa Fe layers down-dropped to the
west.
0.9
45.6 Crossroad; TURN AROUND, carefully. Road to right to Cochiti Dam on
the Rio Grande; left to Kaiser Gypsum Rosario plant and quarry. The
Jurassic Todilto gypsum is used to make gypsum wall-board. It was
deposited about 150 million years ago in an extensive
34
inland sea that covered most of north-central and northwestern New
Mexico. RETRACE U.S. Highway 85 toward Santa Fe.
0.3
45.9 In right roadcut, local stream gravels that are younger than the Santa Fe
Group beds they overlie. Ahead are badlands cut in reddish layers of the
Galisteo Formation at the base of La Bajada Hill.
0.6
46.5 At bottom of La Bajada Hill, cross fault zone between down-dropped
pinkish-brown Santa Fe beds to west and the reddish Galisteo Formation
to the east. The whitish streaks in the Galisteo are lenses and nodules of
"lime," calcium carbonate and some gypsum.
1.8
48.3 High roadcut on right of greenish-gray Mancos Shale cut by vertical
limburgite dike, overlain by pink "baked" Santa Fe bed and capped by the
black basalt flow.
2.5
50.8 Turn out on right as descend from crest of hill, near convenient high-way
department litter can. View to northeast, across valley of Alamo Creek, of
the Santa Fe area. The city, about 15 miles away, lies snuggled at the foot
of the Sangre de Cristo ("Blood of Christ") Mountains; when the setting
sun strikes them just right, these mountains appear to be a beautiful darkred color. To the right of U.S. 85, a few miles to the west, are the coneshaped hills of Cerro de la Cruz and Bonanza Hill.
1.7
52.5 Bridge across Alamo Creek; cottonwood grove on right fed by spring
water.
VIEW NORTHEAST FROM MILEAGE 50.8 TOWARD SANTA FE
35
PANORAMIC VIEW TO SOUTHWEST. FROM LEFT TO RIGHT, BONANZA HILL, …
0.6
53.1 Junction with N. Mex. 22 from right, south, at Turquoise Trading Post.
About half a mile to the northeast, the highway ascends a small rise; just
off the highway to the right is a black, cone-shaped, pointed hill, Cerro
de la Cruz (hill of the cross). Watch carefully for junction to left with N.
Mex. 22.
0.7
53.8 TURN LEFT onto black-topped N. Mex. 22 to Cienega. Cross cattle
guard just off U.S. 85 and STOP for views.
STOP H. Looking back toward the highway, you can see the following
landmark features in a panoramic view from east to west, clockwise in
order:
Bonanza Hill
Turquoise Hill in saddle
Cerro de la Cruz
Cerrillos (Ortiz Mountains in saddle of Cerrillos)
Sandia Mountains
highway to Albuquerque
volcano just west of highway (source of several lava flows)
canyon of Santa Fe River cutting into the lava mesa (Mesa Negra)
Tetilla Peak
Jemez Mountains on skyline
36
…CERRO DE LA CRUZ, CERRILLOS, SANDIA MOUNTAINS, AND HIGHWAY
Cerro Seguro—the rounded black knob this side of the mesa
Cerros del Rio—shrub-covered high mesa to northwest and
just to the north of us a wet valley—water again
"Cienega" means "marsh" or "miry place"—there are many seeps and
springs. Grass is green in the valley of Cienega Creek, and irrigation
ditches line the sides. Where does this water come from? The arroyos
between here and Santa Fe are dry and sandy.
The mountains east of Santa Fe are made of fairly impermeable rock,
so both rain and melting snow run out onto the plain and seep into the
sandy channel fill of the numerous arroyos. Hard summer rains on the
plain also soak in fairly quickly. The water seeps slowly westward toward
the Rio Grande, for the rock under the plain is sand and gravel. But at
Cienega, there are several kinds of volcanic rocks, all practically
impermeable. This rock is a barrier to groundwater movement, and so the
water comes to the surface. The quiet old community of Cienega has for
many years diverted this discharging ground water for irrigation along the
narrow valley of Cienega Creek.
0.9
54.7 Abandoned Cienega school on right, as descend into valley of Cienega
Creek. Behind and to north is St. Joseph Church. Knob behind school and
the one ahead of us are part of a dike (a vertical, crosscutting igneous rock
sheet) shown as "d" on the sketch map.
37
VIEW TO NORTHWEST ALONG CIENEGA ROAD. LEFT OF ROAD, JEMEZ MOUNTAINS ON …
0.1
54.8 Bridge across Cienega Creek.
0.1
54.9 STOP I. Pavement ends; dirt road ahead leads left, west, to a local ranch;
right, it follows Cienega Creek upstream.
The geologic history of the Cienega area has been pieced together by
geologists from the many rock outcrops. With the help of the map of the
Cienega area, you can drive along each of the roads and see the main
features. The vertical relationships are shown on the cross section.
The central part of the area consists of monzonite, the gray-brown rock
with the small, light-gray feldspar crystals. The monzonite was once a
pasty mass of molten rock that forced its way up through other rocks as
an igneous intrusion. The Galisteo Formation (the red beds which you
saw on the way down from the highway), and some volcanic breccia
southwest of the monzonite were tilted by this intrusion. Later the surface
was worn down by streams to expose the monzonite.
Next, two sets of volcanic breccias and flows of the Espinaso volcanics
were poured out onto the surface. These breccias can be seen just east of
the dam (marked on the Cienega map). On the southwest side of the dam,
there are elongated holes in the rock—these were gas bubbles that were
stretched as the lava moved. The cliffs northeast of the dam along the
road show the nature of the volcanic breccias
38
…SKYLINE AND TETILLA PEAK; TO RIGHT, CERRO SEGURO AND CERROS DE RIO
ON SKYLINE
clearly (photograph). Small and large blocks of volcanic rock are embedded in fine-grained volcanic material. These volcanic breccias are
common in many parts of New Mexico and represent lava flows or ash
flows that picked up blocks of earlier formed rock.
The breccias were buried by flows of the Cieneguilla limburgite, a
basaltlike black lava that forms cliffs between Cieneguilla and Canyon
along the Santa Fe River. The hill with the white mission cross and Cerro
Seguro are made of limburgite, as is the cap of Cerro de la Cruz. Cerro de
la Cruz is not a complete volcanic cone, but it may be the core or plug of
a former volcano.
All these volcanic rocks probably were formed in Oligocene–Miocene
time. Later faulting has tilted the volcanic breccias and offset some of the
strata of rock. A fault can be seen north of the road that leads toward the
Gallegos ranch. Here the monzonite is faulted up against red beds of the
Galisteo Formation.
Before leaving the Cienega area, notice two other kinds of rock, the
gravel and the mesa-capping lava, which belong in a later part of the
story. The gravel (not shown on the map) underlies the lava west of the
Santa Fe River and blankets most of the rest of the Cienega area. However, hills of the volcanic rocks were not all buried under the gravel and
lava flows. The monzonite and the limburgite are resistant to erosion and
both form knobs that stand above the level of Mesa Negra.
39
MAP AND CROSS SECTION OF ROCK UNITS IN THE CIENEGA AREA
b, basalt flows; A, Ancha Formation (not shown on map); C, Cieneguilla limburgite; v, Espinaso
volcanics; m, monzonite; G, Galisteo Formation; d, dike (not shown on section); dashed line,
boundaries of rock units; faults indicated by D/U (D—down, U—Up).
40
RUGGED CLIFFS OF ESPINASO VOLCANIC BRECCIA ALONG CIENEGA CREEK
54.9 Leave STOP I; TURN RIGHT, eastward and follow the unpaved road as
it parallels Cienega Creek through the scenic farming community.
0.7
55.6 Espinaso volcanic rocks, here volcanic breccias, in cliffs on left.
55.9
0.3
Junction, TAKE LEFT FORK. Right fork follows an arroyo for about 2
miles, then crosses the mesa and rejoins U.S. 85 (I-25) about half a mile
south of the junction with N. Mex. 10.
2.0
57.9 Cross cattle guard after driving under telephone line on flat mesa. In onefourth mile, begin descent into valley of Santa Fe River.
0.6
58.5 Cieneguilla; small church a quarter of a mile on left; sharp RIGHT TURN
at base of the bluff; road then angles across the Santa Fe River flood
plain. The channel from Santa Fe downstream to Cieneguilla is a broad
sandy arroyo flanked by terraces (former, higher, stream floors). This
sandy stream bed, usually dry, is in marked contrast with the running
water and narrow canyon of the Cienega area. (But do not risk this "dry"
arroyo during or after stormy weather!)
0.4
58.9 Cross to west side of Santa Fe River arroyo.
41
0.6
59.5 Junction, KEEP RIGHT, along side of arroyo. The cinder pit on the
hillside to the west was once part of a volcanic cone; it was later buried
by a lava flow.
2.3
61.8 Cross to south side of Santa Fe River and drive up onto main terrace.
0.2
62.0 Sewage plant on left.
1.3
63.3 TURN LEFT onto black-topped road from municipal airport. In less than
a mile, Santa Fe Municipal Golf Course is on right.
2.7
66.0 Junction with U.S. 85, Cerrillos Road. Follow direction signs and TURN
LEFT onto Cerrillos Road toward Santa Fe.
6.0
72.0 Santa Fe PLAZA—altitude 6990 feet.
End of Trip 3.
CLOSE-UP OP VOLCANIC BRECCIAS
42
Trip 4
MIOCENE TO PLEISTOCENE
Buckman Road
THE SANTA FE BEDS
The rise of the Sangre de Cristo Mountains and the filling of the Rio Grande
trough with sand and gravel and with lava flows are the important last chapter
of our story; the final page is recorded in the downcutting of the present
streams.
Back in 1869, F. V. Hayden made a geologic reconnaissance in the Santa Fe
area. He originated the name "Santa Fe" for the beds of sand and gravel, partly
consolidated into ledge-forming rocks, that crop out from Galisteo Creek north
toward Taos. More recent geologic studies have shown that the Santa Fe beds
accumulated as "basin-filling" sediments during the formation of the Rio
Grande trough, from Miocene to Pleistocene time. Perhaps the trough is still
actively deepening. The movement, which began in the Miocene, has been
primarily along faults, or breaks, rather than a result of warping or folding. As
the mountains slowly rose and the trough subsided, the streams brought more
and more sand and silt and gravel into the basins that make up the trough. Near
Los Lunas, southwest of Albuquerque, the basin fill is more than 2 miles thick!
In the Santa Fe area, some of the details of this basin filling can be seen.
Toward the end of the volcanism that we noted around Cienega, volcanic ash
was blown into the air and settled down over a large area. The whitish ash beds
around Arroyo Hondo and Bishop's Lodge belong to this stage of Miocene time.
At about the same time, the present Sangre de Cristo Mountains began to rise
along faults trending north and north-northwest. The long straight valley
traversed by U.S. 85, 5 to 10 miles southeast of Santa Fe, was eroded along one
of these faults. Streams, invigorated by the steeper slopes, carried sand and silt
westward to pile up several thousand feet of basin-fill.
If we had been here some 10 or 15 million years ago, about at the end of the
Miocene epoch, we would have noticed frequent stream floods carrying debris
down from the mountains east of us, but even in a lifetime we would not have
been particularly impressed with the accumulation of sediments. If the main
amount of basin-fill accumulated in only a million years, a rate of an inch every
ten years would result in nearly 10,000 feet of sediment! This thick part of the
Santa Fe beds, characterized by ledge-forming soft sandstones exposed north of
the city, is called the Tesuque Formation; a typical exposure is shown in the
photograph.
43
The Tesuque Formation around Pojoaque and Española has yielded abundant
bones and teeth of the horses, deer, camels, bears, and other mammals that lived
during the late Miocene and early Pliocene. The nature and abundance of fossils
indicated a fairly moist climate and grassy plains, and generally good living
conditions. Collections and studies of fossils of these beds have been made
since 1880, and the Frick Laboratory of the American Museum of Natural
History is making an intensive study of the fossils.
At some time in the Pliocene epoch, the Tesuque sediments were in turn
broken by faults and tilted westward about 10 degrees. A prominent westwardsloping fault block just north of Pojoaque can be seen from U.S. 285 north of
Santa Fe. At the same time, there was a final upfaulting of the Sangre de Cristo
Mountains. The plains west of the mountains were eroded, for the Tesuque
Formation is absent both at the "Garden of the Gods" (Stop F) and at Cienega.
The gravel at both of these places belongs to the Ancha Formation, the next
younger unit of the Santa Fe beds.
The erosion in the Pliocene produced a westward-sloping plain, although
some of the volcanic rocks around the Cerrillos and Cienega stood as hills
above this plain. Eventually the plain was buried under the sand and gravel of
what we call the Ancha Formation. The relationships of the Ancha Formation
are seen on Trip 4.
The westward-sloping surface was covered by cinders from volcanoes, such
as the cinder pit north of Cieneguilla, and then was buried under lava flows.
The eastern limit of the flows was about the position of the present cliff of
basalt along the west edge of the Santa Fe area. Here the lava is only 50 feet
thick, but it is several hundred feet thick in White Rock Canyon opposite
Frijoles Canyon. A water well on the mesa encountered 1000 feet of basalt,
although some of this thickness is probably of an earlier set of flows that form
the high, dissected mesa of the Cerros del Rio.
VIEW SOUTHEAST TOWARD THE SANGRE DE, CRISTO MOUNTAINS, 10 MILES
NORTH OF SANTA FE; TESUQUE FORMATION IN MIDDLEGROUND
44
DIKE WITH UNCONFORMITY
With the outpouring of basaltic lava west of the Santa Fe area, the streams
that drained westward from the mountains were dammed up. The Santa Fe
River was turned southward toward Cienega by the flows. Erosion and
deposition were only minor for part of the Pleistocene.
Now our story shifts to the Jemez Mountains. Volcanic activity that continued through Ancha time had by now formed a magnificent towering
mountain. The mountain may have been capped with snow and ice, and there
were glaciers high in the Sangre de Cristo Mountains, too. The climax of
volcanic activity took place in a few fiery months. Pumice was blown out over a
wide area. Shortly afterward, great volumes of hot volcanic ash flowed
eastward from the crater. The ash flows filled canyons that had been cut in the
basalt—a 500-foot buried canyon can be seen in Frijoles Canyon below the
Bandelier Monument—and diverted the ancestral course of the Rio Grande. If
you drive up toward Bandelier National Monument on N. Mex. 4, you will see
this sequence near the junction of the highway leading to Los Alamos; basalt is
overlain by pumice, which in turn is overlain by the tan, cliff-forming ash
flows.
With the outpouring of the pumice and ash, the mountain peak subsided or
collapsed. All that remains is a circular "caldera," and Valle Grande is part
45
of this depression. The rim of the caldera, which measures 16 miles across—one
of the largest known in the world—forms the mountains just west of Los
Alamos.
Fortunately, some of the pumice was blown across the Santa Fe area, and so
we can correlate the events around Santa Fe with the volcanic history of the
Jemez Mountains. The pumice indicated in the sketch of buried land surfaces is
5 miles south of the Buckman road, but another deposit can be seen along U.S.
85, 8.7 miles southwest of the Plaza. These and other pumice deposits occur in a
band trending southeast across the center of the Santa Fe area.
Although we cannot give accurate geologic dates for the post-Tesuque
events, the basaltic flows are possibly early Pleistocene and the pumice slightly
later. Faulting produced the scarp at La Bajada, southwest of Santa Fe, and the
waterfall of the diverted Santa Fe River began cutting headward, forming the
400-foot canyon below Cienega. By the time the waterfall had reached Cienega,
the river upstream had brought in the volumes of gravel seen around the village.
The gravelly floor of the valley of this ancestral river has proved to be fairly
resistant to erosion, and so when downcutting of streams in the present cycle
began, two streams took over the work. The present Santa Fe River is on the
north side and Arroyo de los Chamisos on the south. Other drainage
modifications of this recent vintage include the course of the Santa Fe River
through narrow canyons in the Cienega area and the headwater diversions of
creeks in the mountains.
The last trip takes us to the northwest corner of the Santa Fe area, where
Cañada Ancha drains northwest at the base of the lava mesa in a youthful
course.
Buckman Road northwest of the Plaza to see the rocks and buried surfaces of
the Santa Fe beds. Round trip, 24 miles; driving time, 45 minutes.
0.0 Leave Plaza on north-west corner at west end of Palace of Governors.
Drive west past Art Museum for one block; TURN RIGHT onto Grant
Avenue and after a half block, TURN LEFT at traffic light onto Johnson
Street. Drive west two
blocks.
0.4
0.4 Junction with U.S. 285-8464, Jefferson Street; TURN
RIGHT,
north
onto
highway.
46
NEW ME XICO MUSEUM OF ART
0.4
0.8 Rosario Chapel cemetery on right. Legend has it that De Vargas camped
here before retaking Santa Fe in 1892 and built a chapel, part of which
comprises today's Rosario Chapel. He attributed his victory of reconquest
to La Conquistadora, represented by a statuette of the Blessed Virgin that
he brought with him. Although normally honored in a side chapel of the
Cathedral, the statuette becomes the focus of a religious procession early
each summer to return it to the Rosario Chapel for a period of veneration
of the Virgin.
0.2
1.0 Santa Fe National Cemetery to right, one of the 97 in the country and
analogous to Arlington National Cemetery in Virginia. Title to the
original land was donated by the Roman Catholic Diocese of Santa Fe
through Bishop John B. Lamy on July 2, 1870. Initial interments at the
site were the remains of United States' soldiers from the Civil War battle
of Glorieta. Among others buried here are Governor Charles Bent,
General Patrick J. Hurley, and Oliver LaFarge.
0.2
1.2 TURN LEFT off highway.
0.2
1.4 Cross, carefully, North St. Francis Drive onto Alamo Drive.
47
BURIED LAND SURFACES NORTHWEST OF SANTA FE
0.3
1.7 TURN RIGHT onto Camino de las Crucitas; pavement ends in half a
block; go up hill on dirt road. Well-exposed outcrops of Tesuque
Formation in roadcuts.
0.3
2.0 Junction where Arroyo Torreon crosses; TAKE RIGHT FORK.
0.1
2.1 Junction, TAKE LEFT FORK.
0.6
2.7 Road crosses abandoned railroad grade as it did at Arroyo Torreon; as you
climb onto ridge top, notice this railroad grade to the north along north
bank of Arroyo de los Frijoles, to right. This railroad once extended up
the Rio Grande into Colorado. For the first 6 miles from Santa Fe, the
stream and roadcuts show the westward-dipping, soft sandstone and
siltstone of the Tesuque Formation.
1.6
4.3 Cross sandy channel of Arroyo de los Frijoles; take LEFT FORK at top of
hill on northwest side of valley.
0.5
4.8 Junction, TAKE RIGHT FORK.
1.0
5.8 Cross sandy arroyo.
0.4
6.2 Cross Arroyo Calabazas (where are the pumpkins?).
48
0.3
6.5 Top of hill; TAKE LEFT FORK. Cerros del Rio straight ahead and Jemez
Mountains on skyline.
0.9
7.4 Cattle guard.
0.2
7.6 Junction, continue straight ahead on LEFT FORK, cross cattle guard.
Ranch road to right.
0.8
8.4 STOP J. Here the road begins to drop off the upland surface. A thin bed of
gray-black basalt cinders (tuff) crosses the road here. The cinders forming
the tuff bed were spewed from one or several of the volcanoes that dot the
lava mesa, and they were deposited in a few weeks—an instant of
geologic time. They thus rest on a former land surface. From Stop J
eastward for 2 miles, the tuff is on the Tesuque Formation, and from here
westward it is on the Ancha Formation, as indicated in the sketch of the
buried land surfaces. Careful geologic mapping along the arroyos that are
cutting down through the sequence of former land surfaces has shown that
the Ancha Formation rests on a westward-sloping surface that cut across
the tilted Tesuque Formation, and the cinders preserve a second buried
land surface. The upland remnants are all that is left of a third surface now
being eroded by streams.
1.7
10.1 Road joins abandoned railroad grade in valley of Alamo Creek. The
PALACE OF THE GOVERNORS ON NORTH SIDE OF PLAZA
49
hills nearby are made up of the gravels and sands of the Ancha Formation;
about 200 feet of the Ancha underlie the basalt-capped mesa ahead—ten
times the thickness of the Ancha Formation at Stop J.
2.0
12.1 Windmill. The road follows the railroad and arroyo (Canada Ancha) north
to Buckman, an abandoned community, and joins N. Mex. 4 west of
Pojoaque, but it crosses private property. Turn around and return to Santa
Fe.
End of Trip 4.
50
Conclusion
In these brief trips near Santa Fe, we have had glimpses of past landscapes.
Moreover, it is now evident that modern landscapes are transient. How old,
then, are the Sangre de Cristo Mountains, for example? Well, they are made of
Precambrian and Pennsylvanian rocks, and so the rocks are a quarter of a
billion to perhaps a billion years old. These rocks were forced up into the
mountains about the end of the Cretaceous Period, some 70 million years ago,
and though they were then eroded to a low elevation, some vestiges of the "first
shaping" remain. The rocks were faulted up to their present heights during
"Santa Fe time," beginning perhaps 15 million years ago and continuing almost
to the present. Modeling of these heights is fairly recent, going back scarcely
before the Pleistocene, and this phase is still going on. In the next 100,000
years, the climate may return to glacial conditions, and in future millions of
years, mountain-building may be renewed—or it may be going on today!
THE MAP ENDS HERE TOO
51
Some Additional Reading
If you wish to learn more about geology, the following books will help:
Geology—Merit Badge Series: Boy Scouts of America, 1953. (An excellent
introductory booklet on geology.)
The Rock Book: C. L. and M. A. Fenton, Doubleday, Doran & Co., Inc.,
1940. (About minerals and rocks.)
The Rocky Mountains: Wallace W. Atwood, Vanguard Press, 1945.
(Geology, scenery, folklore, and landforms of the Rockies.)
If you wish to read more about the geology of this region :
Tertiary geology of the Galisteo—Tonque area, New Mexico: Charles E.
Stearns, Bulletin of the Geological Society of America, 1953, vol. 64, p.
459-508. (This is a recent study with a good list of other pertinent geologic
articles; for the geologist.)
Crater Lake, the story of its origin: Howell Williams, University of California
Press, Berkeley and Los Angeles, 1941. (This is the fascinating story of a
caldera, with a history similar to that of the Jemez Mountains, as told by a
park ranger to people who had never looked at rocks before.)
Mining districts of New Mexico; Cerrillos: Charles L. Knaus, New Mexico
Miner, Oct. 1951 (p. 13), Dec. 1951 (p. 10), and Feb. 1952 (p. 12). (An
easily read summary of a well-known mining district.)
Mosaic of New Mexico's scenery, rocks, and history: Paige W. Christiansen
and Frank E. Kottlowski, New Mexico Bureau of Mines and Mineral
Resources, Scenic Trips No. 8, 1967. (Descriptions of geology of Santa Fe
area and the rest of the state, as well as articles on history, plants, animals,
and other interesting facets of New Mexico.)
Geology and water resources of the Santa Fe area, New Mexico: Zane
Spiegel and Brewster Baldwin with contributions by other authors, U.S.
Geological Survey, Water-Supply Paper 1525, 1963. (Technical
description of geology, water resources, and geophysics of the Santa Fe
area.)
TOPOGRAPHIC MAPS
Topographic maps are available for about 60 per cent of the State of New
Mexico. These maps, prepared by the U.S. Geological Survey, show cultural
and drainage features, such as houses, wells, roads, streams, and arroyos, and
they depict the topography by contour lines of elevation. Earlier maps have been
on a scale of either 1 or 2 miles to the inch. Currently, however, much of northcentral New Mexico is being mapped on a scale of 2000 feet to the inch,
including the area around Santa Fe. Each map costs only 50 cents and is
available from either the U.S. Geological Survey, Federal Center, Denver,
Colorado 80225, or from the New Mexico Bureau of Mines and Mineral
Resources, Socorro, New Mexico 87801. The maps should be ordered by
quadrangle name; these names are listed on the index to mapping. The latter is
available without charge from either of the two agencies.